Assessing the cost-effectiveness of invasive species management: a decision tool for biodiversity conservation

Invasive species threaten biodiversity in Australia. One of these species is the introduced root pathogen Phytophthora cinnamomi, which harms native and commercial plant species. Disease caused by this pathogen was listed as a key threatening process under the Commonwealth's Environment Protection and Biodiversity Conservation Act in 2000. There is considerable uncertainty regarding the best management strategies to address invasive species like Phytophthora cinnamomi; particularly where the efficacy of control methods is unknown. How should environmental managers decide whether management strategies are worthwhile or cost-effective? We demonstrate the use of a tool that can address these management challenges: the Investment Framework for Environmental Resources (INFFER). INFFER was designed to help environmental managers achieve the most valuable environmental outcomes with the limited resources they have available. The framework involves a systematic assessment of the trade-offs between variables such as asset value, likelihood that private individuals will adopt management or behavioural changes, delays in the realisation of benefits, and sources of uncertainty due to potential technical failure or socio-political risks. We present an application of INFFER to assess the cost-effectiveness of management strategies to address Phytophthora cinnamomi in the Fitzgerald River National Park, a national park in the South-West Botanical Province of Western Australia. The Fitzgerald River National Park is one of the largest parks in Australia, and has high conservation value because of its high floral diversity and numbers of endemic species. The model was developed in collaboration with park stakeholders, including park rangers, management and research officers, and members of a local natural resource management group. We found that despite uncertainty regarding the efficacy of existing containment and eradication methods, management strategies aimed at containing existing Phytophthora cinnamomi infestations and preventing future infestations, resulted in significantly greater benefits than costs (Benefit: Cost Index = 3.02). This result supports investment of public conservation funds to control Phytophthora cinnamomi in the Fitzgerald River National Park. A sensitivity analysis identified the need for better biophysical data to quantify the impact of management works, and demonstrated how uncertain funding environments prevent confidence in the accomplishment of project goals, through an inability to assure the future maintenance and upkeep of management works. Our analysis demonstrates the importance of using a rigorous decision support tool like INFFER to assess investment decisions when there is uncertainty regarding conservation benefits